1,5-Di(4-amidinophenoxy)pentane, which is generically known as pentamidine, has for many years been known for use as a pharmaceutical, in particular for the treatment of the early stages of African trypanosomiasis (`sleeping sickness`). Pentamidine has also been found to be effective in the treatment of pneumo-cystis carinii pneumonia (PCP), a condition which is commonly contracted by patients with acquired immuno-deficiency syndrome (AIDS) and also by cancer and organ transplant patients. It has been estimated that some 65% of AIDS patients develop PCP. Amongst such patients the condition is life-threatening.
PCP infection in AIDS patients using pentamidine has been by intravenous infusion or intramuscular injection although this treatment is often accompanied by severe side-effects, eg hypotension, renal failure and hypoglycaemia. More recently, there has been reported (Abstracts of the Annual Meeting of the American Society of Microbiology 86, 14 (1986)) a method for the prevention of PCP which comprises the administration by inhalation of a nebulised aqueous solution of pentamidine.
A problem which has hitherto been encountered with the use of aqueous solutions of pentamidine is that such solutions, which have a pH in the range 4.5 to 6.5, are not stable and must therefore be made up immediately prior to use.